2011 Annual Report of NWT Wildlife Research Permits and Western ...

Wildlife Species Research:
Caribou
OBJECTIVES:
´ ´ To estimate the composition of the South Nahanni
and Coal River mountain caribou herds, specifically
recruitment (calf:cow) and sex (bull:cow) ratios; and
´ ´ To collect spatial information on seasonal distribution
patterns of the South Nahanni caribou herd.
METHODS:
For both the South Nahanni and Coal River herds
a helicopter was used to fly at or above treeline,
focussing on high plateaus, which are areas known
to be used by mountain caribou during the rut. Routes
were flown and areas chosen so as to avoid doublecounting
of animals. When a group was observed, its
composition was assessed and animals were classified
into one of five categories: calves, adult female, immature
male, mature male, or unclassified. All attempts were
made to classify each animal in a group. The locations
(latitude /longitude) of groups were recorded using GPS.
Spatial location data from the South Nahanni herd is
obtained from satellite collared adult females. Thirty
females were collared in 2008 and will be monitored
through 2012.
LONG-TERM PLANS .
AND RECOMMENDATIONS:
Remaining satellite collars will be monitored during the
next year to provide more precise estimates of seasonal
distribution and movement patterns. This was the final
year of planned monitoring for these herds in this four-year
project. During 2012/2013, a detailed report synthesizing
all information including composition surveys, population
estimates, and satellite collar information will be prepared.
COMMUNITY INVOLVEMENT:
Copies of this and all other reports are provided to
communities and Boards. Throughout this long-term
project efforts have been made to have community
members on survey flights when possible and to date
we have had observers from Tulita and Watson Lake
participate on the surveys. Observers for the 2011 survey
were Troy Hegel, Matt Clarke, and Ryan Drummond,
all with Environment Yukon.
RESULTS AND MAIN CONCLUSIONS:
In the South Nahanni survey (~ 14 hours of flying), 484
animals were classified resulting in a calf:cow ratio of
24.7 calves:100 cows, and a sex ratio of 43.9 bulls:100
cows. In the Coal River survey (~ 12 hours of flying), 271
animals were classified resulting in a calf:cow ratio of
35.2 calves:100 cows, and a sex ratio of 32.1 bulls:100
cows. Calf recruitment in both herds was similar to those
in 2010 and higher than in previous years (2008, 2009).
This may be due to more favorable weather conditions
at calving during the 2010 and 2011 springs. This level of
recruitment generally follows a pattern observed in other
mountain caribou herds across the Yukon this year.
Coal River mountain caribou herd.
Photo: T. Hegel
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